Solid ink or phase change ink printers conventionally receive ink in a solid form, sometimes referred to as solid ink sticks. The solid ink sticks are typically inserted through an insertion opening of an ink loader for the printer, and are moved by a feed mechanism and/or gravity toward a heater plate. The heater plate melts the solid ink impinging on the plate into a liquid that is delivered to a printhead assembly for jetting onto a recording medium. The recording medium is typically paper or a liquid layer supported by an intermediate imaging member, such as a metal drum or belt.
A printhead assembly of a phase change ink printer typically includes one or more printheads each having a plurality of ink jets from which drops of melted solid ink are ejected towards the recording medium. The ink jets of a printhead receive the melted ink from an ink supply chamber, or manifold, in the printhead which, in turn, receives ink from a source, such as a melted ink reservoir or an ink cartridge. Each ink jet includes a channel having one end connected to the ink supply manifold. The other end of the ink channel has an orifice, or nozzle, for ejecting drops of ink. The nozzles of the ink jets may be formed in an aperture, or nozzle plate that has openings corresponding to the nozzles of the ink jets. During operation, drop ejecting signals activate actuators in the ink jets to expel drops of fluid from the ink jet nozzles onto the recording medium. By selectively activating the actuators of the ink jets to eject drops as the recording medium and/or printhead assembly are moved relative to each other, the deposited drops can be precisely patterned to form particular text and graphic images on the recording medium.
One difficulty faced by fluid ink jet systems is nozzle contamination resulting in partially or completely blocked ink jets. Nozzle contamination may be caused by dust, paper fibers, dried ink, etc. that accumulates on the nozzle plate of a print head. Tests have shown that a phase change ink jet printer may be at risk for nozzle contamination during warm-up of the printer from a powered down or standby state, to an operational state. For example, as the print head warms up, the solid ink that has solidified or frozen in the print head melts and expands in the print head, causing melted ink to drool out of the nozzles onto the nozzle plate. By the time the printer has warmed up sufficiently to perform printing operations, however, the ink that has drooled out of the nozzles onto the nozzle plate may be sucked back into the nozzles. The ink that is drawn back into the print head may potentially draw contamination from the nozzle plate into the nozzles.